1. Field of the Invention
The invention relates to a rotary sleeve bearing apparatus for a rotary compressor in which a rotary sleeve is rotatably mounted in the center housing for rotation with a plurality of vanes and floatingly supported by an air bearing formed between the outer periphery of the rotary sleeve and the inner periphery of the center housing.
2. Description of the Prior Art
A movable vane compressor of the type having a rotary sleeve mounted within an air-bearing room defined between the outer periphery of the rotary sleeve and the inner periphery of the center housing is free from frictional heat and wear at the apex of each vane and, therefore, suitably used as a supercharger for an automobile engine required to run over a wide range of low to high speeds. However, there is the possibility of scuffing and seizing troubles if the rotary sleeve makes a frictional contact with the center housing when it is pushed from within to the inner periphery of the center housing by air compressed in the compression working space confined among the rotary sleeve, the rotor, and the adjacent vanes. From experimental results that the outer periphery of the rotary sleeve contacts the compression side inner periphery of the center housing not on a line but on an area, the inventors of this application have proposed, under Japanese Patent Application Ser. No. Sho 58-28608, that a rotary compressor is provided with an inlet disposed at the starting point of the contact area in the compression side inner periphery of the center housing and an air-supply passage extending from the inlet to the open air, the discharge chamber, or the compression working space whereby air is supplied to the contact area to increase the bearing capacity of the air-bearing room. The inlet is desirably connected to the working space under the maximum pressure to supply the maximum pressure air to the air-bearing room. But, there is a problem that the air supply is insufficient, in volume and pressure, to prevent a direct contact between the rotary sleeve and the center housing when the rotor runs at a rotational speed above a limit in which the amount of air to be supplied to the air-bearing room exceeds what can be extracted from the working space.